In the semiconductor device manufacturing industry, advanced semiconductor high performance integrated circuits require that the materials used as interlayer and intermetal dielectrics decrease the RC delay of the interconnects and also reduce the crosstalk between metal lines. Low dielectric constant (low-k) materials have been developed and continue to be developed for this purpose. The particular dielectric constant of the materials used for interlayer or intermetal dielectrics is critical for device performance. It is therefore imperative to accurately measure the dielectric constant of a formed low-k dielectric film. It would be advantageous to measure the dielectric constant on a product substrate during processing, i.e., a substrate that continues to be processed and to have integrated circuits or other semiconductor devices formed thereon. It would also be advantageous to be able to measure the dielectric constant without having to form a particular structure dedicated to such measurement. Finally, it would be advantageous to measure the dielectric constant in a manner that does not damage or alter the film.
Present methods for measuring dielectric constant include use of a mercury (Hg) probe. This technique requires a specific MOS structure to be created for such measurement. Furthermore, a mercury dot contacts a surface of a low-k film producing contamination concerns for further processing. The surface contact may furthermore bring about other film quality maintenance concerns. Another method for measuring dielectric constant is the MIS (metal-insulator-semiconductor) (CAT) but this also requires a specific MOS structure for measurement and requires a formation of a metal electrode on the substrate. Yet another technique is the interdigitated comb which requires the formation of an interdigitated comb structure on the substrate. While the interdigitated comb technique produces accurate data, data collection is not real-time as the substrate being measured must be removed from production because the dielectric constant extraction requires extensive cross-sectioning and Raphael modeling. In sum, the shortcomings of conventional techniques for measuring the dielectric constant of a low-k dielectric film include surface contact, the requirement to produce a particular dedicated measurement structure, the lack of real-time data and the requirement to permanently remove the tested substrate from the production environment.
The dielectric constant is a frequency dependent, intrinsic material property. It consists of three components that result from electronic, ionic and dipolar polarization. The individual components of the overall dielectric constant are impacted by different phenomena and processees associated with semiconductor device manufacturing. It would therefore be desirable to measure or derive each of the three components as well as the overall dielectric constant.
It would therefore be ultimately desirable to provide a non-contact measurement technique that yields each of the components of the dielectric constant and the overall dielectric constant of a low-k dielectric film for a substrate that continues to be processed and which does not require formation of a particular test structure.